Apparatus and methods are known to produce pass-through catalytic substrates for treating exhaust from gasoline and diesel fueled internal combustion engines. It is known to provide a honeycomb substrate with catalyst coatings within the flow channels of the substrate. In operation, exhaust gas is forced to pass through the flow channels of the substrate. When passing through the flow channels, pollutants like unburned hydrocarbons, carbon monoxide, nitric and nitrous oxides react on catalysts in the washcoatings to form innocuous species like nitrogen, carbon dioxide, and water before the exhaust is released to the atmosphere.
During a typical engine start up, a significant amount of time may pass before the pass-through catalytic substrate is heated to a temperatures where the catalyst is active and capable of processing the pollutants. Consequently, a significant amount of pollution escapes immediately after the engine is started and before the substrate reaches the light-off temperature. As such, in order to reduce excess pollution during engine start-up, there is a desire to provide pass-through catalytic substrates to support the catalyst washcoatings that can be quickly heated to reduce the time necessary to reach the light-off temperature.